Extend the Domain Mapping Plugin

I'm working on a in-house plugin for WordPress Multisite that isn't intended to be released and is going to be used on our production environments.

The my plugin interacts with your domain mapping plugin. I was wondering if you can briefly help me.

1. Can you please tell me the function or global $var I can call that would display the current blogs "primary mapped domain".

2. Can you please tell me the function or global $var I can call that would display the "Health status" of that primary domain. Such as Valid/Invalid

Thank you very much